A Brasilian campaign called "Virtual Racism, Real Consequences" has placed Billboards in the home towns of racist internet denizens featuring their hurtful posts alongside a blurred out image and username of the offender. The project used Facebook's geo-tagging function to locate the commenters.
The organizers of the project don't want to identify anyone or give trolls more attention which is why the identifying information is blurred out. They hope that people who made these comments will come across their own words in a very public venue and realize the impact of their comments has more reach than the semi-anonymty of the internet.
They have also created a video to better explain their efforts :